Add Button to Cases Subpanel

[DaneGerous]

I've been searching reading and pulling out my hair for a couple of days now.
I have gotten only so far and need some guidance on the last parts.

I am putting a simple CRM together. Only two modules 'Accounts' and 'Cases'
'Cases' should actually be called Cert Informations. I have attached an image
that Is very descriptive of what I'm actually trying to accomplish.

I have managed to get two instances of edit but can't seem to get my own
button to show up. I'm comfortable with editing PHP but I just can't find where
I need to put what. Here is the code that the print button would execute.

 <?php
require('num2txt.php');

$img = imagecreate(1320,900);
$color = imagecolorallocate($img, 0xFF, 0xFF, 0xFF);
$font = 'DejaVuSerif-Bold.ttf';
$fontItalic = 'DejaVuSerif-BoldItalic.ttf';
$fontCalli = 'Amazone.ttf';
$black = imagecolorallocate($img, 0, 0, 0);
$red = imagecolorallocate($img, 255, 0, 0);
//Name Handling
$name = "";
$bboxname = imagettfbbox(18, 0, $fontItalic, $name);
$namecent = $bboxname[2]/2;
//Shares Handling
$shares = "4500";
$bboxshares = imagettfbbox(14, 0, $font, $shares);
$sharescent = $bboxshares[2]/2;
$date = $today = date("F j, Y");
// Add the text
$ispreferred = '1';

if($ispreferred == '1'){
imagettftext($img, 12, 0, 620, 360, $red, $font, "PREFERRED");//Preferred under Company Name
}
imagettftext($img, 14, 0, 1065-$sharescent, 210, $black, $font, number_format($shares));    //Number of shares
imagettftext($img, 18, 0, 665-$namecent, 510, $black, $fontItalic, $name); //name
imagettftext($img, 14, 0, 220, 552, $black, $fontItalic, convertNum($shares));//Spelled out Shares
imagettftext($img, 20, 0, 180, 740, $black, $fontCalli, $date);//Spelled out Shares
header ("Content-type: image/jpeg"); // Let teh system know to generate an image
ImagePNG($img,"pic.png"); 
$command="lp -d Cert_Print pic.png";  //      Send command to Unix OS lpr command
exec($command);         //      Send the command string directly to the operating system */
imagedestroy($img);
?>  

In the end it would print a Stock Cert with the pertinent information, I can get
it to print properly manually but I would like to get that button on that Cases
sub panel ..

You don't have to 100% Tutorialize me, I just need some locations where I
can find the files that I need to edit to make this printing process easier,

Maybe Others Can Benefit from my above code. I have an Hp Laser Printer
attached through USB. This may seem like cheap and dirty coding but it
totally serves its purpose.

You would save me a lot of hair plugs in the long run >,< ..

Thanks DaneGer